The media is reporting that the Society of Obstetricians and Gynaecologists of Canada (SOGC) no longer recommends routine cesarean when the baby is presenting breech at term. The new clinical practice guideline entitled "Vaginal Delivery of Breech Presentation" concludes that "vaginal delivery is reasonable in selected women with a term singleton breech fetus."

Automatic cesarean for breech has been the international standard of care since the results of the Term Breech Trial (TBT), a multicenter, randomized controlled trial of over 2,000 women that was designed to "give the option of vaginal breech delivery its best, and perhaps last, chance to be proven a reasonable method of delivery." That chance appeared to be dashed with the release of the trial's findings, which seemed to suggest that vaginal breech birth posed unacceptable risks to the baby. The results included:

• combined stillbirth and neonatal mortality rate excluding lethal congenital abnormalities: 0.3% in the planned c-section group vs. 1.25% in the planned vaginal group
• combined perinatal mortality and serious neonatal morbidity: 1.6% in the planned c-section group vs. 5.0% in the planned vaginal group
• no differences in maternal mortality or morbidity between groups

There has not been another randomized controlled trial of term breech birth since the TBT. So in the absence of any new "Level 1 evidence," what explains SOGC's new endorsement of vaginal breech birth and their commitment to retrain their obstetric and midwifery workforce to ensure the option remains a safe one? The journey to routine cesarean and back provides an important lesson in the nuances of evidence-based medicine. Let's take a look at how the evidence has unfolded.

First, over the months and years following the trial's publication, a flurry of responses poured in from clinicians and researchers around the world, pointing to flaws and irregularities in the trial, suggesting that labor care in some of the trial hospitals was not optimal, and claiming a failure of adequate peer review by The Lancet, the journal that had fast-tracked it to publication. (These problems are summarized in Henci Goer's critique, When Research is Flawed: Planned Vaginal Birth versus Elective Cesarean for Breech Birth.) Cracks in the evidence were already appearing.

Then, after two years, the TBT research team tracked down the trial participants and reported long-term health outcomes. This new data revealed that almost all of the babies with severe morbidity after birth in both trial groups survived without any long-term neurological compromise, and differences in combined mortality and morbidity between the cesarean and vaginal groups had disappeared. The new SOGC Guidelines note:

With the limitations in the TBT, women had a 97% chance of having a neurologically normal two-year old, regardless of planned mode of birth. Those randomized to a trial of labour had a 6% absolute lower chance (or 30% relative risk reduction) of having a two-year-old child with unspecified medical problems, suggesting some lasting benefit of labour to the newborn immune system.

Meanwhile, several large non-randomized studies were released, consistently reporting excellent outcomes of planned vaginal breech birth. The largest, a prospective cohort study four times the size of the TBT, compared outcomes of planned vaginal birth versus elective cesarean for breech in 174 French and Belgian hospitals. There was no difference in perinatal mortality (0.08% vs. 0.15%) or serious neonatal morbidity (1.6% vs. 1.45%) between planned vaginal and planned cesarean birth. While not randomized, this robust and well designed study provided strong evidence that the risks of vaginal breech birth can be minimized in modern obstetrical units that adhere to rigorous practice standards for care in breech labor and birth.

The growing body of research set the stage for a new policy, but SOGC's change of heart was clearly also influenced by a vocal and persistent group of consumers and clinicians who pushed back against routine cesarean for breech. A few brave doctors and midwives saw the TBT results not as a dictum about whether breech vaginal birth is safe, but as an invitation to study how it could be made safer. They also recognized the ethical problems inherent in coercing women to accept the risks of surgery in exchange for little if any benefit to their infants, and lamented the hoops women must jump through to obtain a safe vaginal breech birth in the post-TBT era.

This story is still unfolding. We do not yet know if the change in guidelines will translate to a meaningful change in practice, or for that matter, whether we will see a similar guideline revision south-of-the-border. But I am heartened to see that we are moving forward from a rigid hierarchy of evidence, where randomized controlled trials - methodologically sound or otherwise - represent absolute truth and trump consumers' rights to informed consent and refusal. In this new era of health care quality improvement, views on the intersection of evidence-based practice and consumer preference are evolving. The story of the Term Breech Trial and its aftermath reminds us that even when the landmark clinical trial is done, there is still room for more and better research and grassroots advocacy to hone our understanding of optimal practice in maternity care and ensure access to options that are safe and satisfying.Click on the extended post for a bibliography.

Goffinet, F., Carayol, M., Foidart, J. M., Alexander, S., Uzan, S., Subtil, D., et al. (2006). Is planned vaginal delivery for breech presentation at term still an option? results of an observational prospective survey in france and belgium. American Journal of Obstetrics and Gynecology, 194(4), 1002-1011.

Hannah, M. E., Hannah, W. J., Hewson, S. A., Hodnett, E. D., Saigal, S., & Willan, A. R. (2000). Planned caesarean section versus planned vaginal birth for breech presentation at term: A randomised multicentre trial. term breech trial collaborative group. Lancet, 356(9239), 1375-1383.

Hodnett, E. D., Hannah, M. E., Hewson, S., Whyte, H., Amankwah, K., Cheng, M., et al. (2005). Mothers' views of their childbirth experiences 2 years after planned caesarean versus planned vaginal birth for breech presentation at term, in the international randomized term breech trial.Journal of Obstetrics and Gynaecology Canada, 27(3), 224-231.

Kotaska, A. (2004). Inappropriate use of randomised trials to evaluate complex phenomena: Case study of vaginal breech delivery. BMJ (Clinical Research Ed.), 329(7473), 1039-1042.

Whyte, H., Hannah, M. E., Saigal, S., Hannah, W. J., Hewson, S., Amankwah, K., et al. (2004). Outcomes of children at 2 years after planned cesarean birth versus planned vaginal birth for breech presentation at term: The international randomized term breech trial. American Journal of Obstetrics and Gynecology, 191(3), 864-871.

Published: June 17, 2009

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